Vehicle drive and steer mechanism



United States Patent 72] Inventor Anton M. Rel'fle Chi g Illinois [21Appl. No. 750,260

[22] Filed Aug. 5, 1968 [45] Patented Oct. 20, 1970 [73] Assignee EatonYale & Towne Inc.

Cleveland, Ohio a corporation of Ohio [54] VEHICLE DRIVE AND STEERMECHANISM Primary ExaminerA. Harry Levy Att0rneyTeagno and ToddyABSTRACT: A material handling apparatus comprises a load support carriedby front wheels and rear wheels. Means is provided for driving the rearwheels to power the apparatus. Moreover, a steering mechanism isprovided for moving the rear wheels to effect steering thereof. The rearwheels are carried by a support plate which is pivotal about ahorizontal axis. Pivotal mounting of the support plate permits the rearwheels to be disposed at different vertical distances from the loadsupport. First and second motors are utilized for driving first andsecond rear wheels, and these motors are removably mounted on theunderside of the plate and extend downwardly therefrom. The motors drivevertically extending drive shafts which rotate to effect rotation of thedriving wheels about a horizontal axis through a pinion and ring gearset. The wheels which are driven by the drive shafts are supported byspaced supports for rotation about the axes of the respective verticaldrive shafts by the steering mechanism for steering purposes. Thesteering mechanism includes a link member which is pivotally connectedto the spaced supports and which is movable in a generally endwisedirection to effect pivoting movement of the supports about the axes ofthe drive shafts. The construction and relationship of the link to thesupports is such that a form of geometric steering is accomplished.

Patented Oct. 20, 1970 3,534,825

Sheet 1 of 4 FIGI INVENTOR. ANTON M REFFLE o/E gr Arm/W578 Patented Oct.

Sheet INVENTOR. ANT N M. REFFLE Patented Oct. 20, 1970 Sheet 6 a w 5 3 QW 3 r 9 ml v INVENTOR. ANTON M. REFFLE A TTORNEYS Patented Oct. 20, 1970Sheet INVENTOR. ANTON M. REFFLE VEHICLE DRIVE AND STEER MECHANISM Thepresent invention relates to a material handling apparatus, andparticularly relates to a material handling apparatus of the lift trucktype having drive wheels which are also steered for purposes of bothdriving and steering the apparatus.

The principal object of the present invention is the provision of a newand improved material handling apparatus which includes steerabledriving wheels and where the drive for the wheels and the steeringthereof are effected in a manner to provide for turning the materialhandling apparatus in extremely narrow aisles and small spaces and, yet,maintain substantially full lateral stability for the apparatus duringthe turning by maintaining a substantially constant tread widthdimension.

A further object of the present invention is the provision of a new andimproved material handling apparatus which has steerable driving wheelsand wherein the mechanism for steering and driving the wheels is acompact structure requiring a minimum of space and, yet, is extremelyreliable in operation and relatively simple in construction.

Another object of the present invention is the provision of a new andimproved material handling apparatus having driving rear wheels and asteering mechanism for steering the rear wheels which includes a meansfor simultaneously moving a first rear wheel a first angular distanceabout a first steering axis and a second rear wheel a second angulardistance greater than the first angular distance about a second steeringaxis spaced from the first steering axis to provide for steering of thevehicle in extremely narrow spaces while maintaining the vehicleextremely stable.

A still further object of the present invention is the provision of anew and improved material handling apparatus having driving wheelscarried on a support plate which is pivotal about a horizontal axis andwherein the driving wheels are driven by a plurality of motors which arecarried by the support plate and which are mounted on the undersidethereof and extend downwardly therefrom, thus providing a compactstructure requiring a minimum of space on the apparatus.

Still another object of the present invention is the provision of a newand improved material handling apparatus having rear driving wheelswhich are driven upon rotation of spaced drive shafts and which aresupported by first and second supports which are pivotal about the axisof the drive shafts for steering purposes, and wherein a steeringmechanism is provided for steering the wheels to effect pivoting of saidwheels about said drive shaft axes for steering purposes with thesteering mechanism including a link member which is generally U- shapedso as not to interfere with the pivoting movement of the wheels.

A further object of the present invention is the provision of a new andimproved material handling apparatus, as defined in the next precedingobject. wherein the U-shaped link member is pivotally connected at itsopposite ends with the wheel supports and wherein the pivotalconnections of the link members to the rear wheel supports are spaced agreater distance than the distance between the steering axes for theserespective wheels.

Further objects and advantages of the present invention will be apparentto those skilled in the art to which it relates from I the followingdetailed description of a preferred embodiment thereof made withreference to the accompanyingdrawings in which:

FIG. 1 is a schematic, partially sectional, side elevational view of amaterial handling apparatus embodying the present invention;

" and illustrating the steering mechanism of the vehicle;

FIG. 2 is a schematic view, taken along the line 2-2 of FIG. I

FIG. 5 is a partial sectional view of the apparatus shown in FIG. 3taken along the section line 5-5 of H6. 3; and

FIG. 6 is a schematic view of the apparatus of FlG. l illustrating thesteering wheels in a steered position and showing further features ofthe invention of the present case.

The present invention provides a new and improved materi als handlingapparatus, and particularly provides a new and improved materialshandling apparatus having driving wheels which are also steered forpurposes of driving and steering the materials handling apparatus. Thepresent invention, in a preferred embodimentthereof, is in a materialshandling apparatus of the lift trucl ;type. The invention may be used inmaterials handling apparatus of different constructions and specificallylift trucks of different construction.

As representative of the present invention, the drawings illustrate theinvention embodied in a lift truck 10. The lift truck 10 includes a loadsupport ll which carries the operator of the vehicle and on which thevarious operator-actuator controls are carried. The support ill carriesat its forward end a lift construction, generally designated 12, andwhich can be vertically moved along mast 13. The lift constructionengages and carries a load in the convention and well-known manner, andaccordingly, further description thereof will not be made.

The lift truck 10 includes a plurality of front wheels, designated 19,and two sets l6, 17 of rear wheels. The front and rear wheels carry theload support 111 and the lift structure 12. The front wheels arerotatable about a common fixed axis. The set 16 of rear wheels includesa pair of wheels 26a, 20b and the set 17 of rear wheels includes wheels200, 2%.

The rear wheels of the vehicle are powered or driven so as to effectmovement of the lift truck 10 along the surface on which the lift truckis operating. Each set of rear wheels 24M, 20!: and 20c, 20d are drivenby separate drive means El, 22, respectively. The drive means 21 whicheffects driving of the set 16 of rear wheels 20a, 20b is identical tothe drive means 22 which effects rotation of the set 17 of rear wheels20c and 20d and, therefore, only the drive means 2i for effectingrotation of the wheels Zlla and 20b will be described herein in detail.

The drive means 21 which effects rotation of the wheels Mia and 20bincludes a motor 25 which is supported in the materials handlingapparatus lit in a manner to be described hereinbelow. The motor 25 uponrotation drives a gear 26 which, in

turn, meshes with a gear 27 which is carried on a shaft 28 which carriesa gear 29. The gear 29 upon rotation effects rotation of an idler gear30 which meshes with the gear 29 and which also meshes with a gear Fall.The gear 31 is drivingly connected with a vertically extending driveshaft 32 which has a bevel pinion 33 on the end thereof adjacent the setof rear wheels 16. The bevel pinion 33 projects downwardly between thewheels 20a and 20b and drives the ring gear 34 of a conventionaldifferential 35. It should be apparent that the motor 25 uponenergization will drive the vertically extending drive shaft 32 and thedrive shaft will in turn, effect rotation of the wheels 20a and 20babout a horizontal axis through the operation of the differential 35.

As noted above, the drive means 22 for the wheels 20c, 20d is identicalin operation to the drive means 21 and includes a motor, generallydesignated 40 in FIG. 2, which drives the wheels 20c, 2011 throughgearing similar to that described in connection with wheels 20a, 2012, avertically extending drive shaft 41. corresponding with shaft 32 and adifferential. it is to be noted, however, that the drive shaft 41 isdrivingly associated with pinion and ring gears in such a manner thatrotation of the drive shaft 41 in a direction opposite to the directionof rotation of the drive shaft 32 results in rotation of the wheel set17 in the same direction as wheel set 16. The importance of this featurewill be further described hereinbelow.

The motors 25 and 40 are supported by a horizontally extending plate 50.The motors specifically are removably secured to the underside of theplate 50 and extend downwardly and are disposed immediately adjacent tothe rear wheels which they drive. This provides a compact structurerequiring a minimum of space.

The plate 50, as noted, supports both motor 25 and motor 40 at spacedlocations thereon. The plate 50 is supported, at a position intermediatethe motors, for pivotal movement about an axis 51 of a pivot pin. Thegears 26, 27, 28, 29, 30 and 31 are all supported by the support plate50 is apparent from the drawings.

The support plate 50 also has a bore 53 located therein which receives avertically extending sleeve member 54 in which the drive shaft 32 islocated and through which the drive shaft 32 extends. The sleeve 54 isrotatably mounted by spaced bearings 55 and 56 for rotation in the bore53 about the axis thereof. which coincides with the axis of rotation ofthe drive shaft 32. The lower end of the sleeve 54 terminates in aflange portion 57 which has spaced generally vertical plate portions 59and 60 which extend downwardly therefrom and are located between thewheels 20a, 20b and support the wheels for pivotal movement relative tosaid support plate 50.

It should be apparent from the above description that one set of rearwheels 16, 17 could be disposed at a different vertical distance fromthe load support 11 of the vehicle than the other set of rear wheels.More specifically, it should be apparent that the rear wheels can tiltwith respect to the support 11 about the shaft 51 of the support plate50. This tilting movement results when the surface on which the lifttruck is moved, is uneven or slanted. The sets of wheels can compensatetherefor merely by the pivoting action of the plate 50 about the axis ofthe pin 51. It should be apparent, of course, that the axis of pivotingmovement of the plate 50 extends transverse to the axis G of rotation ofthe wheels in anunsteered position U and is located intermediate thesets 16. 17 of wheels.

It should be further apparent from the description hereinabove that thesleeve member 54 is rotatable in the bore 53 and upon rotation thereofin the bore 53 about the axis of the bore, the support for the wheels a,20b, namely. the flange portion 57 and the plates 59, 60 will alsorotate about the axis of the drive shaft 32. In order to effect steeringof the vehicle 10, a steering mechanism, generally designated 70, isprovided to effect rotation of the sets of wheels 20a, 20b about theaxis of rotation of the drive shaft 32 and the set of wheels 20c, 20dabout the axes of rotation of the drive shaft 41.

Thus, the axes of the drive shafts which transmit the rotary motion fromthe motors and 40 to the sets of wheels 20a, 20b and 20c, 20d constitutesteering axes for those respective sets of wheels. These steering axesare shown and designated A and B, in FIG. 4.,

The steering mechanism 70 is constructed so as to provide for steeringof the materials handling apparatus 10 in extremely narrow aisles andspaces without greatly affecting the stability of the vehicle.

The steering mechanism is of the type which provides for geometric, wideangle steering.

Referring to FIG. 6, the geometric, wide angle steering, provides thatthe vehicle is steered, in either direction, about points, which lie onthe axis C of rotation of the front wheels 19 of the vehicle. As shownin FIG. 6, wherein the wheels have been rotated by the steeringmechanism 70 from an unsteered position U to the maximum steeredpositions R, L in which positions the steering is effected about pointsD, D located approximately along the lateral edges of the vehicle and onthe intersections of the axes G, Gand G', G" where G represents the axesof rotation when the wheels l6, 17 are in the unsteered position U. Itshould also be apparent from FIG.

16. It should be apparent from FIG. 4 that the distance E between theaxis of the pivot pins 72, 73 is greater than distance F between thesteering axes A and B. This distance is a result of the fact that theaxes of the pivot pins 72, 73 are disposed in opposite directions fromrespective lines which extend through the steering axes A and B andperpendicular to the axis G of rotation of the rear wheels. Morespecifically, the axes of the pins 72, 73 are disposed approximately 3from these lines, as shown in FIG.'4.

The link member 71 is moved in a generally endwise manner in order toeffect pivoting movement of the sets of rear wheels 16, 17 about thesteering axes A, B, respectively. The endwise movement of the link 71 iseffected in the preferred embodiment by a power means in the form of adouble acting hydraulic cylinder 80. The hydraulic cylinder 80 ispivotally connected to the link 71 by a pivot pin 81 located at one endthereof. The hydraulic cylinder 80 is also pivotally connected at 82 tothe support plate 50. The hydraulic cylinder 80 is operated to effectmovement of the link 71, and thereby effect steering of the materialshandling apparatus 10, in a conventional manner by means of suitablecontrols and valving, which are well known in the art and will not bedescribed herein in detail.

Due to the particular construction described hereinabove and therelationship of the distances between axes of the pins 72, 73 and thesteering axes A, B, the link 71, upon movement thereof by the powermeans 80, effects movement of the sets of wheels 16, 17, respectively,through different angular distances about the respective steering axes Aand B. This should be apparent upon viewing FIG. 4 wherein the set ofwheels 17 has been moved an angular distance X, as indicated by theangular distance of movement of the pin 73, whereas the angular distanceof movement of the set of wheels 16, as indicated by the movement of thepivot pin 72, is an angular distance Y. It should be clearly apparentthat the angular distance Y is substantially in excess of the angulardistance X and is on the order of 13 greater. Due to the geometry of theconstruction described, the apparatus 10 will be steered about points D,D located along the axis of rotation C of the front wheels 19 of thevehicle, as noted hereinabove when the wheels l6, 17 are rotated to themaximum steering positions shown in FIG. 6, thereby enabling it to beturned in very narrow spaces. In steering from the unsteered position Utoward the fully steered positions R, L, the intersection of the axes G,G" and G', G"" will occur on the axis C of the front wheels 19 atvarying lateral distances from the points D, D depending on thedirection and amount of steering angle. This, of

course, is recognized as a preferred manner of steering and constitutesan important feature of the invention case particularly in view ofrelatively simple construction for accomplishing this desirable result.

Another important feature of the present invention is the comparativeease with which the motors 25, 40 may be removed for servicing andreplacement when necessary. As can be seen in FIG. 4, the motor 25 isremovably secured to the plate 50 by a plurality of fasteners 83. Theplate 50 has a generally circular opening 84 therethrough through whichthe motor shaft 85 and gear 26 extend. The opening 84 is sufficientlylarge as to permit passage of the gear 26 therethrough withoutobstruction. It can be seen therefore, that motor servicing andreplacement may be accomplished when necessary in an extremely simplemanner. No other structure of the 6 that the steering mechanism 70 hasmoved the sets of rear matefl'als handling apparatus 10 need be disturbin Order 10 wheels different angular distances about the steering axes Aand B.

The link member 71, best shown in FIG. 4, is of a generally U-shapedconstruction and has a base portion 7la and opposite leg portions 71band 710. The leg portion 7lb is pivotally connected by a pivot pin 72 tothe flange portion 57 forming a portion of the support for the set ofwheels 16. The other end of the leg portion 710 of the link 71 islikewise pivotally connected to a support portion 77 for the set ofwheels 17 correplace the motors 25, 40 nor is it necessary tounnaturally shift the position of the apparatus 10, such as by jacks orotherwise, in order to perform the necessary services on the raptors.

' Further to be noted, by reference to the statement made above' thatthe drive shafts 32, 41 are driven in rotationally opposite directionswhile driving the wheels 16, 17 in the same rotational direction, isthat the torque, necessary to drive the apparatus, from the drive motors25, 40 acts in opposite responding with the support portion 57 for theset of wheels directions and is effectively reacted by the steering link71 with no adverse effect on the force necessary to steer the apparatus.

While the present invention has been described hereinabove inconsiderable detail, it should be apparent that certain modifications,changes, and adaptations may be made therein. and it is intended tocover all such changes, modifications, and adaptations which come withinthe scope of the appended claims.

lclaim:

l. A materials handling apparatus comprising a support, front wheels andrear wheels carrying said support:

separate drive means for driving such of said rear wheels to power saidsupport, each of said drive means including a substantially verticallyextending drive shaft;

a plate pivotally mounted on said support, said plate supporting saidrear wheels for pivotal movement about a horizontal axis and said drivemeans includes a plurality of motors one of which is drivinglyassociated with each of said drive shafts, each of said motors beingmounted on the underside of said plate and extending downwardlytherefrom; and

a steering mechanism for pivotally moving said rear wheels to effectsteering thereof, said steering mechanism including means supplyingpower for simultaneously moving a first rear wheel a first angulardistance about a first vertical steering axis and a second rear wheel asecond different angular distance about a second vertical steering axisand wherein driving and steering of said rear wheels occurs along acommon vertical axis, said first steering axis corresponding with theaxis of rotation of one drive shaft for one rear wheel and said secondsteering axis corresponding with the axis of rotation of another driveshaft for the second rear wheel.

2. Materials handling apparatus as defined in claim 1 wherein saidsupport plate defines a plurality of openings through which at least aportion of each of said plurality of motors extends, and fastening meansremovably securing said motors to said support plate.

3. Apparatus as defined in claim 1 wherein said steering mechanismincludes a member operatively connected with said first and second rearwheels and movable to effect movement of said first and second rearwheels about said first and second vertical axes respectively, and saidmeans for supplying power includes a fluid-powered cylinder pivotallyconnected with said plate and having a piston rod pivotally connectedwith said member for effecting movement of said member.

4. Apparatus as defined in claim 3 wherein said motors rotate said driveshafts in opposite directions of rotation.

5. A materials handling apparatus comprising a support, a plurality ofdriving wheels carrying said support, means supporting said drivingwheels for pivotal movement about a horizontal axis so that said wheelsmay be disposed at different vertical distances from said support, saidmeans comprising a plate supporting said wheels and pivoted about thehorizontal axis, a plurality of motors mounted on the underside of saidplate, extending downwardly therefrom and disposed adjacent said wheels,separate drive means supported by said plate and drivingly connectingeach motor with at least one drive wheel for rotating said drive wheelabout a general horizontal axis and means for rotating said wheels abouta vertical axis relative to said plate to effect steering of saidapparatus:

wherein said drive means includes a vertically extending drive shaft foreach of said driving wheels, and said steering mechanism comprises meansfor effecting pivotal movement of said driving wheels about spacedsteering axes which correspond with the axes of rotation of said driveshafts.

6. A materials handling apparatus as defined in claim 5 wherein saidsteering mechanism comprises a link member operatively connected atopposite ends thereof with spaced rear wheels and power means pivotallyconnected with said link and pivotally connected with said plate foreffecting said pivotal movement of said rear wheels.

